Resonace device for pianos



Nov. 4 1924.

J. H. WILLIAMS RESONANCE DEVICE FOR PIANOS Filed March 1920 3 Sheets-Sheet 1 l I I I i I Nov. 4, 1924. 1,514,493

J. H. WILLIAMS RESONANCE DEVICE FOR PIANOS Filed March 5. 1920 3 Sheets-Sheet 2 V i 5! vw emtoz 5 gjmafZ/fi Z Zmms Warm M @511 GHQ an Nov. 4 1924.

J. H. WILLIAMS RESONANCE DEVICE FOR PIANOS 3 Shaets-Sheet 3 Filed March 5. 1920 Patented Nov. 4, 1924.

UNITED STATES JAMES H. WILLIAMS, OF BALTIMORE, I/IARYLAND.

RESONANCE DEVICE FOR PIANOS.

Application fi led March 5, 1920. Serial No. 363,429.

To all whom it may concern Be it known that I, JAMns H. rimmers, a citizen of the United States, residing at Baltimore, in the county of Baltimore City and State of Maryland, have invented new and useful Improvements in Resonance Devices for Pianos, of which the following is a specification.

My present invention relates to improvements in pianos, and the primary object of the invention is to provide a novel and improved back frame for pianos, whereby the volume of tone and its duration are substantially increased, and the quality of the tone improved. These results are accom plished by constructing within the braces or supports of the back or backing of the piano, a resonating chamber or chambers of substantial length, the air within such chamber or chambers being set into vibration by the sound board which is set into vibration by the striking of the strings by the usual hammers or other sound-producing instrumentalities of the piano, the resonating or air chambers thus acting to amplify the volume of air set in motion and hence the volume of sound produced, to prolong its duration, and to otherwise improve its quality.

Another feature of the invention coniprises a main bridge formed interiorly with a resonating or air chamber which acts to increase the volume and to prolong the duration of the sound and otherwise improve the quality of tone.

To these and other ends, the invention consists in certain improvements and combinations and arrangements of parts, all as will be hereinafter more fully described, the features of novelty being pointed out particularly in the claims at the end of the specification.

In the accompanying drawing Figure l is a rear elevation of an upright piano constructed in accordance with the preferred embodiment of the invention;

Figure 2 represents a horizontal section through the back of the piano, taken on the line 2-2 of Figure 1;

Figure 3 represents a vertical section through the back of the piano, taken on the line 33 of Figure l;

Fi 'ure d is a detail section taken vertically through the back of the piano on the line 4t of Figure 1;

Figure 0 is a front elevation of the back shown in Figure 1, the sound board and other parts being removed;

Figure 6 represents a section taken on the line 6-6 of Figure 5;

Figure 7 is a front elevation of the back showing the sound board, the iron frame and other parts in position thereon, and illustrating an improved sound board bridge; and

Figure 8 represents a section through the bridge and the sound board to which it is attached.

Similar parts are designated by the same reference characters in the several views.

The present invention is applicable generally to pianos of various kinds which employ a back or backing composed of a suitable number of braces or supports or other structural elements which are usually of solid or nonresonant construction, and the improved bridge is applicable to pianos of all types. The preferred embodiment of the invention is shown in the accompanying drawing and will be hereinafter described in detail. It is to be understood, however, that the invention is not restricted to the particular embodiment shown, as equivalent constructions or applications of the invention are contemplated and these will be ineluded within the scope of the claims.

In the present embodiment, the invention is shown for example applied to an upright piano wherein l designates generally the back, 2 designates the sound board which is glued or otherwise mounted on the front side of the back, 3 designates the main bridge which is glued on the front side of the sound board and over which the strings pass, and 4 designates the iron frame which is mounted in front of the sound board and carries the strings, the strings being set into vibration by the usual hammers. The back, in this instance, comprises a suitable numher of supports or posts 5, four of which are shown, as an example in the present instance, and upper and lower horizontal brace members 6 which intervene between and connect the supports or posts. These supports or posts, and their connecting brace members constitute a rigid frame or back for the piano to which the outer case and also the sound board, iron frame and the various other parts and mechanisms of the piano are usually secured, this back or frame being composed usually and preferably of wood? of a suitable kind;

According to one feature of the present invent-ion, resonating or air chambers of'a suitable number are formed within the back, these air chambers having openings through which vibrations, set up by the strings in front of the SOllllCl board, and taken up by the sound board, are transmitted to the columnsof air in these air chambers, thus setting into vibration these columns of air in tlie'air chambers. An increasediamount of resonance is thus obtained, which amplifies the volume oftll'e sound and increases. the period of its duration, and the fullness and other qualities of the tone are improved. Preferably and asshown, each support or post is provided with an interior vertical air chamber 7, each of these air chambers communicating with the space in front of the back through openings or vents 8. Preferably and as shown, a relatively thin strip of wood or similar material 9 is glued or otherwise suitably applied to the front of each post so as to cover the respective air chambers, except for theopening or vent 8 which is formedat oneor more points in the strip, These air chambers 7 are preferably ofja lengith nearly equal tothe length of the supports or posts. The intervening or con necting brace members 6, also preferably are.forme d with airchambers 10 which extend longitudinally of thesemembers, and serve to connect the upper, and lower ends respectively ofthe air chambers T in the upright supports or posts. Preferably the frontsides of'the air chambers in the lower brace members are closed by a relatively thin strip of wood or similar, material 11, and the front sides of theair chambers in the upper. brace members are covered by a board 12 to whiclrthe top otthe iron frame 4 is attached. These air chambers within the back are preferably. closed" at all sides, except for the openings or vents8,andfhence they form air columns of considerablelength, hen the piano. is played, ,the sound vibrations pro duced by the'striking of" the hammers upon the-strings, set the sound; board into vibration, and the vibrations are transmitted to the; columns of air contained in the air chambers, the resonance afforded by these air" chambers amplifying the volume of sound, andinereasing the duration thereof; and givin other improved qualities to the tone.

b thjer ways of constructing the back to contain thefton'e or resonating chambers, andalso other structural parts of the piano may be constructed to contain tone or resonatin'g chambers such as those described, as will be obvious to those skilled" in this art. For example, another feature oft-he present invention, which is applicable to. pianos,

. whether oi the upright, grand'or other types,

is herein shown as applied to the main bridge 3 which is usually glued to the front of the sound board and serves as a support upon which the vibrating strings of the piano rest. In applying the invention to the main bridge, the bridge, which is generally of laminated construction as shown, is grooved on the side thereof which is to be applied to thesound board, asat 13, the soundboard closing or forming one wall of the groove when the bridge is applied thereto, and. one or more openings or vents 1 iare formed in a side of the bridge and communicate with the interior air chamber formed by the groove. The air chamber within the bridge provides an air column which is set into vibration by the vibrations of the adjacent soundboard and the strings bearing; thereon with the result that the volume and duration of the sound produced by the sounding. of

the strings, and especially those for the upper notes, are increased and the tone is otherwise improved in quality.

Thus it will be noted that essentially: the invention consists in providing a piano or like structure with terminally limited or confined or obstructed resonating chambers, or in other words, elongated chambers or channels whereof the extremities in the line of the length thereof are obstructed, stoppedor limited or interrupted, so that the columns of air confined within said chambers or channels are limited in longitudinal expansion, to the end that the vibration of these columns of air consist in alternate expansion and contraction thereof. ()r, in other words, essentially the invention consists in providing the piano structure and more especially the sound board supporting frame or members of the frame with reverberatory chambers, which may be, and are preferably, as indicated in the drawings, connectedin series in adjoining members of the frame so that these several columns of air contained respectively in, the chambers or channels formed respectively in the several members of the frame, while being terminally obstructed to produce rever beratory chambers in that the longitudinal extension or expansion of the columns. of air is limited, are in communication later.- ally near their ends to provide for a 00111 munication of vibrations or pulsations from one chamber'or channel to another. These columns of air contained in the chambers or channels thus constitute sensitive vibratory mediums exposed laterally by reason of the lateral ports and also by reason of the relatively thin walls of the channels presented in some instances, as described, toward the plane of the sound board, so that the vibrations of the sound board and of the air set in motion by the vibrations of the sound board and in adjacent. relation to the members of the frame, which supports the sound board, are taken up and reproduced and prolonged by the columns of air in the reverberatory chambers.

Moreover, said vibratory mediums being of a volume particularly susceptible to the shorter vibrations of the overtones or harmonics which are produced coincidentally with the fundamental tones at any pitch which may be produced by the instrument, are adapted to take up and prolong or sustain the vibrations of said overtones or harmonics and thus maintain indefinitely, and for a much longer period than in practice is ordinarily attainable, those vibrations which enter into the composition of the tone and constitute the distinguishing characteristics thereof. It is a matter of common knowledge that every tone producing agency, such as a piano or like stringed instrument and likewise the voice, produces composite or complex tones consisting of what are known as partials, including the fundamental which is the pitch denoting partial and harmonics which represent the characteristics of the tone in the matter of fulness, volume, richness and the like, the value in the matter of richness or fulness depending upon the number of overtone or harmonic partials and which are due to the tendency of a string or like medium in vibration, not only to vibrate as a whole throughout its length, but to split up into halves, thirds, quarters, fifths and the like, the divisional points between the partial vibrations being known as the nodal points. Hence, generally speaking, the sounding of each string of an instru ment of the type indicated causes the emission of a sound which is made up not only of a fundamental partial or tone, but of the octave of said tone, the fifth in the octave above the fundamental, the third, and so on in gradually reducing amplitude and rising pitch. It is for the purpose of taking up these partial vibrations or vibrations of fractions of the strings which constitute the harmonics of the fundamental tone sounded and of prolonging said vibrations and thereby maintaining the richness and volume and characteristics of the tones produced by the instrument, that the present structure has been designed.

In instruments of ordinary construction, these harmonics, bot-h consonant and dissonant, are not prolonged, or are not taken up and sustained to any great extent and, therefore, become gradually and more or less rapidly diminished, after the tone has been produced, so that after a relatively brief period the only distinguishable sound is that due to the fundamental vibration or the body vibration of the string which, compared with the original composite tone, is thin and unsatisfactory to the ear, by reason of lacking the characteristic of richness due to the harmonics. The effect of producing reverberatory chambers in the sound board supportingframe of the lli-- strument is to prolong and sustain these harmonics and thereby maintain a softening and mellowing effect and a continuance of the quality, richness and volume which represent the body of the tones.

I claim as my invention A piano having a skeleton soundboard supporting frame composed of marginal members, forming a bearing for the perimeter of the soundboard, and filler or bracing members spanning th space bounded by th first named members and terminally connected therewith, said first and 0nd named members being each provided with a longitudinal channel.

2. A piano having a skeleton soundboard supporting frame composed of marginal members, forming a bearing for the perimeter of the soundboard, and filler or brac ing members spanning the space bounded by the first named members and terminally connected therewith, said first and second named members being each provided. with a longitudinal channel, each of said channels being in terminal communication with the channel of an adjoining member.

8. A piano having a skeleton soundboard supporting frame composed of marginal members, forming a bearing for the per imeter of the soundboard, and filler or bracing members spanning the space bounded by the first named members and terminally connected therewith, said first and second named members being each provided with a longitudinal channel, each of said channels bein in terminal communication with the channel of an adjoining member and having at one side a relatively thin toneresponsive wall.

at. A piano having a skeleton soundboard supporting frame composed of marginal members, forming a continuous bearing for the perimeter of the soundboard, and filler or bracing members spanning the space bounded by the first named members and terminally connected therewith, said first named perimeter supporting members being each provided with a continuous longitudinal channel.

5. A piano having a skeleton sound board supporting frame composed of marginal members, forming a bearing for the perimeter of the soundboard, and filler or bracing members spanning the space bounded by th first named members and terminally connected therewith, said first named perimeter supporting members being each provided with a continuous longitudinal channel having spaced lateral outlets of diametrically reduced area as compared with the channel.

6. An instrument of the piano type hav ing a soundboard supporting frame including a member spaced from the plane of the soundboard and providedwith a longitudinal channel'in communication with the atmosphere through one or more restricted outlets, directed toward and perpendicular to the plane ofthe soundboard.

7. An instrument of the piano type having a frame member provided with a longi- "udinal channel containing a substantially :cufined column of air and covered atone idea by a relatively thin perforated tone responsive Wall.

8. A piano having a sound board supporting frame including marginal and filler or bracing members, provided in their corresponding sides with channels extending longitudinally thereof, a sound board resting upon the marginal members and thin Walls covering and closing the channels of the filler or bracing members and disposed in spaced relation with the plane of the sound board.

9. A piano havin a sound board support ing frame, including marginal and filler or bracing members, provided in their corr sponding sides with channels extending longitudinally thereon a sound board rest-- ing upon the marginal members and thin Walls covering andclosing the channels of thefilleror bracing members and disposed in spaced relation With the plane of the sound board, the channelsin the intersecting marginal members being in communication.

10. A piano having a sound board supporting frame, including marginal and filler or bracing members provided-in their corresponding sides with channels extendin lon itudinall thereof a sound board resting upon the marginal members and thin Walls covering and closing-the chaning upon the marginalmembersand thin Walls covering and closing the channels of the filler or bracing members and disposed in spaced relation with the plane of the sound board, the channels in the marginal and'tiller or bracing members having spaced lateral vents.

12. A piano having a sound board supporting fraine including marginal and filler or bracing members, provided in their corresponding sides with channels extending longitudinally thereof; a sound board resting upon the marginal members and thin Walls covering and closing the'channel's ofthe filler or bracing members and disposed in spaced relation with the plane of the sound board, the channels in the marginal members having vents disposed in parallel relation with the soundboard and those in the filler or-braciiig members having vents disposed in perpendicular relation with the sound board.

In testimony whereof I have hereunto set my hand in presence of two subscribing Witnesses.

JAMES H; WIZLIAB/IS.v I

lVitnesses CHARLES H. SAMLALINO, SAMUEL B; KEILHOLTZ. 

